Comparison of biomolecular force fields for the peptide group and ionic sidechains

A Kirkwood-Buff (KB) derived force field (KBFF) for the computer simulation of aqueous solutions of amides is presented in a recent paper. Here, the KBFF is compared with results from existing force fields for the aqueous solutions of N-methylacetamide (NMA) and the glycine zwitterionic system. NMA represents a model for a peptide group. Glycine, the simplest amino acid, is selected as an example for ionic interactions. Experimental properties such as density, partial molar volume, and heat of mixing, as well as the KB integrals, are compared for a variety of common biomolecular force fields. No one force field, with the exception of KBFF, accurately reproduces the properties of both solutes.